This invention relates to a packaging machine of the type having a pouch making section for forming an elongated strip of interconnected pouches from a flexible web and further having a pouch filling section for filling and sealing the pouches after the pouches have been severed from the strip at the downstream end of the pouch making section. The machine of the invention preferably is of the intermittent motion type in which the web and the pouches are advanced intermittently or step-by-step and in which the pouch forming, filling and sealing operations take place when the web and the pouches dwell between successive steps.
It is well recognized in the packaging machine art that the pouches can be made at a much faster rate than the pouches can be filled since a relatively long dwell period is required to fill the pouches. Even if multiple filling mechanisms are used to fill each pouch during successive dwell periods, the pouch filling section of a standard packaging machine must run at the same velocity as the pouch making section. While the dynamic considerations involved in running the pouch making section at a high velocity can be dealt with, the dynamic factors involved in running the pouch filling section at the same high velocity present a much more difficult problem.
It also has been recognized, for example, in Russell et al U.S. Pat. No. 4,330,288, that advantages can be gained by advancing the pouches broadwise through the pouch filling section rather than edgewise as is conventional in most packaging machines of the type under consideration. By advancing the pouches broadwise through the pouch filling section, the pitch between adjacent pouches can be significantly reduced and thus the velocity required to advance each pouch through a step is decreased so as to ease dynamic demands at the filling section. Moreover, broadwise advance of the pouches through the filling section greatly simplifies changing over of the machine to handle pouches of different widths. By virtue of the broadwise advance, the pitch between the pouches may be maintained the same for pouches of all widths and thus various mechanisms such as the filler and top sealer may be located at the same position for pouches of all widths so as to avoid the need of adjusting the locations of these mechanisms each time the machine is changed over to handle pouches of a different width.
While the Russell et al patent recognizes the advantages of forming pouches while the pouches are advanced edgewise and then filling the pouches during a broadwise advance, the machine disclosed in the patent is very complex and expensive. The machine requires a very sophisticated mechanism for grabbing hold of individual pouches and physically turning each pouch from a position of edgewise advance to a position of broadwise advance.
When pouches are advanced broadwise through a filling section, difficulty also is encountered in opening the pouches preparatory to filling the pouches. One conventional way of opening the pouches is by effecting lateral shifting of the clamps which hold the sides of the pouches. Russell et al U.S. Pat. No. 4,263,768 discloses pouch-holding clamps which are adapted to be moved laterally toward one another in order to pucker the mouth of the pouch into an open condition. This arrangement, however, requires that each clamp be capable of shifting individually relative to the chain which carries the clamp. The clamps are, therefore, complex and expensive.